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I noticed that in the wide world of vertebrate paleontology, not a lot of attention is given to India, despite some rather good Mesozoic (notably Triassic) vertebrate sites. I thought it would be nice to share this with the other TFF members, to promote a bit the advances in Indian vertebrate paleo: https://www.researchgate.net/project/Mesozoic-Microvertebrates
Some of the papers have the full text available.
What do you people think?
-Christian

Hi,
I recently finished processing 4kg of matrix from a horizon in the Upper Hamstead Mbr. of the Bouldnor Fm. from Bouldnor Cliff and thought I'd share the results! The White Band is definitely the most diverse vertebrate fauna I've collected so far in my short time screen washing, with at least 2/3 genera of fish, 2 genera of reptiles, and 2 genera of mammals, it also has some interesting taphonomy.
The White Band refers to a thick Polymesoda shell bed in the Upper Hamstead Mbr. and dates to approximately 33 million years bp during the Rupelian. The Upper Hamstead Member is the youngest strata in the entire paleogene sequence of the Hampshire Basin (Late Palaeocene to Early Oligocene). The horizon was deposited in a shallow freshwater lacustrine environment on the low-lying Solent Group coastal plain of the southern Hampshire Basin. By the time the White Band was deposited average annual temperatures in the region were beginning to warm up again after the sudden and rapid cooling that marked the Eocene-Oligocene transition. Global sea levels were also beginning to rise. The Grande Coupure, the large scale turnover of European mammalian faunas had been and gone, and the endemic Eocene groups such as Palaeotheres, Omomyid primates, and anoplotheres had long vanished. The lake/pond system that deposited the White Band was home to aquatic plants such as Stratiotes and was fringed by patches of open woodlands of Sequoia, Pine, and broadleaf.
With the post-grande coupure fauna now established the landscape was home to anthracotheres, hornless rhinos, hyaenodonts, bear-dogs, entelodonts, primitive ruminants, choeropotamids, and a myriad of smaller mammals including bats, adapid primates, rodents, insectivores, marsupials, and the otter-like pantolestids. Not to mention the alligators, birds, and freshwater turtles.
1. Worn fragment of Emys carapace
2. Possible fragment of crocodilian osteoderm?
3. Fragment of Bowfin skull bone
4. Isoptychus sp. cheek tooth. Theridomyid rodents like Isoptychus are the most commonly found micro-mammal throughout the entire Solent Group. This molar has been heavily worn which may suggest an older individual. Theridomyids were bipedal and foraged along the ground and in low trees. They also seem to have fed on the seeds of marginal aquatic plants such as Stratiotes, which may be the reason this individual was in the vicinity of the pond/lake. The Theridomyids were one of only a few Eocene mammal groups to survive the Grande Coupure and seemed to have survived fairly unscathed in terms of diversity etc. showing what hardy and adaptable rodents they probably were.
5. Fragment of M3 from a talpid, most likely Myxomygale sp. (just 1.5mm long!). Talpids (or as we call them today, Moles) were newcomers to Europe with the Grande-Coupure, arriving from Asia. Belonging to the tribe Urotrichini (Shrew-Moles) which are only found in North America and Asia today, Myxomygale may have spent most of the day underground in burrows before emerging at night to feed on invertebrates. Modern Shrew-Moles prefer moist habitats such as swampy areas, a habitat which was abundant on the low-lying coastal plain of the Oligocene Isle Of Wight.
The taphonomy of the White Band is also interesting. Some specimens i.e. the Emys fragment and osteoderm are highly 'polished' and worn, suggesting transport prior to deposition. Whereas others such as the mammals and most fish material I've recovered are unworn and 'fresh' looking. I'm not sure what conditions could have caused this, and if anyone has any suggestions I'd be really interested. My take is that the mammals and fish were likely living in the immediate area, in and around the lake/pond, whereas the polished material is from animals living some distance away brought to the pond/lake by floods or streams etc. although I'm no trained geologist or palaeontologist.
Thanks for reading,
Theo